1. Field of the Invention
This invention relates to sieves or screens and similar structures of the type utilized in the separation of liquids from solids and, more particularly, to screens fabricated with means disposed at the working surface thereof for supporting the rods or wires thereof in spaced apart and generally parallel relationship.
2. The Prior Art
It has recently become a common practice to separate water and undersized solids from oversized solids present in a slurry by passing the slurry over a cross-flow screen formed with rods or wires extending generally parallel to one another, but generally perpendicular to the direction in which the slurry flows. It has, furthermore, become a common practice to employ such screens as so-called static sieves, i.e., sieves or screens which are supported in an inclined position and which generally remain stationary as a slurry is permitted to flow downwardly over the screen. A difficulty encountered with static sieves of the type under discussion is that as oversized solids separated from the slurry move downwardly over the upper surface of the screen, and the undersized portion of the slurry passes through the screen, water sought to be drained from the under surface of the screen tends to cling, by reason of surface tension and related phenomena, to the underside of the screen where such clinging water is readily reabsorbed upwardly into the solid components traveling over the working surface of the screen. This surface tension problem is aggravated by the presence of supporting hardware associated with the underneath surface of the screen. Such hardware may be in the form of loops formed in the rods or wires, which allow the rods to be assembled to transverse supporting members or cross-rods. Alternately, the hardware may simply comprise weldments formed at the underneath surface of the screen for supporting the screen rods in spaced apart and parallel relationship. Since the liquid or water seeking to pass through the screen must also pass alongside the underlying hardware, the liquid frequently encounters small angularities or gaps between parts which encourage surface tension and capillary phenomena, the effect of which is to accumulate liquids at the underneath surface of the screen. The indicated problem has been recognized in the prior art. U.S. Pat. No. 3,169,111, issued to C. G. Rose et al., teaches the formation of barrier means at the underside of the screen for disrupting films of liquid tending to form at the underside of the screen. U.S. Pat. No. 3,777,893, issued to M. F. Ginaven, teaches the use of curved or bellied wire formations which encourage the liquid passing through a screen to migrate away from underlying supports such as would promote the retention of liquid at the underside of the screen due to surface tension effects.